Heartbeat detecting device and biological signal processing device

Abstract

The difference between the current value and the last value of an RR interval is compared with a predetermined reference differential value, and an attenuation time constant of a peak-hold section is controlled according to the comparison result.

The invention claimed is: 
     
       1. A heartbeat detecting device comprising:
 a peak-hold section that holds the peak of a heartbeat signal; 
 a first adder that outputs a difference signal between an output signal of the peak-hold section and the heartbeat signal; 
 a first comparator that compares the output signal of the first adder with a predetermined reference signal level value; 
 a cycle measuring section that measures the cycle of the output signal of the first comparator; 
 a second adder that outputs the difference between the cycle measurement outputted by the cycle measuring section and the cycle measurement outputted last time by the cycle measuring section; 
 a second comparator that compares the value outputted by the second adder with a predetermined reference differential value; and 
 a time constant controller that controls an attenuation time constant of the peak-hold section according to a logical value of the second comparator. 
 
     
     
       2. The heartbeat detecting device according to  claim 1 , further comprising:
 a delay that causes a delay equivalent to a latency of the peak-hold section, with respect to the heartbeat signal to be supplied to the first adder. 
 
     
     
       3. A biological signal processing device comprising:
 a heartbeat buffer in which heartbeat data is stored, wherein the heartbeat data represents data of a heartbeat signal outputted by a biological signal detecting device that outputs the heartbeat signal of a subject; 
 a heart sound buffer in which heart sound data is stored, wherein the heart sound data represents data of a heart sound signal outputted from a heart sound detecting device that outputs the heart sound signal of the subject; 
 a heartbeat detector that outputs R-wave address information and cut-out address information from the heartbeat data, wherein the R-wave address information indicates the address of an R-wave of a heartbeat waveform, and the cut-out address information indicates the range of the heartbeat waveform; 
 a reposition processing section that cuts out a desired data portion from the heart sound data based on the R-wave address information and the cut-out address information, calculates an RR average, which represents the average value of RR intervals, from the heart sound data stored in the heart sound buffer and the R-wave address information, and repositions the data portion to form repositioned heart sound data; 
 a noise removal processing section that uses an orthogonal transformation and an orthogonal inverse transformation to remove noise components from the repositioned heart sound data to form noise-removed repositioned heart sound data; and 
 a position restoration processing section that uses the R-wave address information and the cut-out address information to resore the position of the noise-removed repositioned heart sound data on the time axis to the state of the heart sound data in the heart sound buffer, 
 wherein the heartbeat detector comprises:
 a peak-hold section that holds the peak of a heartbeat signal; 
 a first adder that outputs a difference signal between an output signal of the peak-hold section and the heartbeat signal; 
 a first comparator that compares the output signal of the first adder with a predetermined reference signal level value; 
 a cycle measuring section that measures the cycle of the output signal of the first comparator; 
 a second adder that outputs the difference between the cycle measurement outputted by the cycle measuring section and the cycle measurement outputted last time by the cycle measuring section; 
 a second comparator that compares the value outputted by the second adder with a predetermined reference differential value; and 
 a time constant controller that controls an attenuation time constant of the peak-hold section according to a logical value of the second comparator.